The CDC reports that a Cambodian father and child were infected with H5N1, resulting in the child’s death. Additionally, Chinese officials report a woman in eastern China recently tested positive for a similar H5N1 strain. However, officials say there’s no indication that the virus has spread from person to person.
On February 25, the CDC announced that two cases of avian influenza A H5N1 (H5N1 bird flu) were reported in Cambodia. The agency says exposure to infected birds or poultry is likely how the individuals contracted the illness.
According to the CDC report, the cases identified occurred in a father and his child. The father reported a fever and cough, and the child died presumably from the infection.
The Cambodia Ministry of Health determined by genetic sequencing that H5 clade 184.108.40.206c — viruses that have circulated among birds and poultry for many years in the region — is what caused the infections.
Although these viruses have caused rare, sporadic infections in humans in the past, none have been reported in Cambodia since 2014.
However, according to CDC officials, the 220.127.116.11c viruses identified in Cambodia are not the same as the H5N1 viruses currently circulating among birds and poultry in the United States and other countries.
At this time, health officials have not identified additional cases, and there’s no indication that the Cambodian H5N1 has spread from person-to-person. The CDC also says that presently, the two human cases identified in Cambodia do not pose a threat to the U.S.
A CDC response team is supporting efforts by the Cambodia Ministry of Health and other global health officials to investigate the infections. The investigation includes contact tracing, monitoring and testing of close contacts, and testing animals in the village.
More recently, Chinese officials reported that a 53-year-old woman from the Jiangsu province in eastern China has tested positive for a similar H5N1 strain. According to a news report, the woman began experiencing symptoms on January 31 after exposure to poultry. Her current condition is unknown.
However, genetic sequencing has identified this strain as the same H5N1 circulating in wild birds and poultry in the U.S.
This latest case follows the September 2022 death of a 38-year-old woman in China after contracting H5N1 from poultry.
The latest update on H5N1 in the U.S.
The U.S. bird flu virus — 18.104.22.168b clade H5N1 bird flu — has caused ongoing and sporadic outbreaks in wild birds and poultry nationwide since 2022. Although the virus has occasionally spilled over to mammals, the CDC says that the current risk of bird flu for the general public remains low.
Since H5N1 was first detected, health officials have monitored more than 6,300 people in more than 50 regions exposed to birds or poultry infected with the virus. Among these individuals, 160 showed flu symptoms. However, investigators only identified H5N1 virus genetic material in a respiratory specimen from one person in Colorado. Moreover, this individual had direct exposure to poultry that may have acquired the virus.
Still, the agency is actively involved in preparing for the possibility of bird-to-human — human-to-human spread of H5N1. For example, CDC diagnostic tests can identify H5N1, and an H5 vaccine candidate is available to produce vaccines against this bird flu type if needed.
In addition, the agency continually analyzes bird flu viruses to detect changes that signal they might spread to people and become capable of spreading human-to-human.